Slow Growth Is Plenty Fast

David Brin’s lead essay made two points:

1. We probably shouldn’t send messages out to aliens now on purpose, and more surely we shouldn’t let each group decide for themselves whether to send.

2. The lack of visible aliens may be explained in part via a strong tendency of all societies to become “feudal,” with elites “suppressing merit competition and mobility, ensuring that status would be inherited” and resulting in “scientific stagnation.”

In my first response, I agreed with Brin on his first point. In this response, I disagree with Brin on his second point.

It is true that before a few hundred years ago wealth and status were often inherited, that most people lived near a subsistence level, and that rates of innovation were low. Today, in contrast, rates of innovation are high, and median incomes are well above subsistence level. This change is called the “industrial revolution,” and it was indeed a good thing.

Brin wants to blame low income and innovation rates before the industrial revolution on elites suppressing merit competition and science. But there is a huge literature on the causes of the industrial revolution, and while there is plenty of disagreement, I’m not aware of anyone who puts stopping elites from suppressing merit competition near the top of their list of plausible causes of the industrial revolution. (My favorite guess: new networks of experts talking.) 

While Brin sees inequality as the main obstacle to innovation, in fact today inequality promotes innovation in important ways. This is because most innovation today happens within for-profit firms, and private for-profit firms put a lot more effort into innovation than do public for-profit firms. Compared to publicly traded firms, privately owned firms invest a 2.5 times larger fraction of their assets, and are 3.5 times more responsive to changes in investment opportunities. Yet private firms cannot exist without great wealth concentration; they are usually owned by fewer than three shareholders, and 83% are managed by the controlling shareholder (Asker et. al. 2011).

Furthermore, the modern world doesn’t actually seem to have much less inheritance of wealth and status than did the ancient world. The detailed work of Greg Clark finds very similar degrees of long-term inheritance around the world today and across history. Specifically Clark finds that the intergenerational correlation of social status remains in the range of 0.7 to 0.8 across all these societies: medieval England, modern England, pre-industrial Sweden, modern Sweden, the United States, Quing and Communist China, Meiji and modern Japan, and Chile (Clark 2014).

But these are only relatively minor criticisms of Brin’s view. My stronger criticism is that the world before the industrial revolution did innovate. Yes, the rate of innovation then was much less than today, but it was still plenty fast enough to create very advanced civilizations within cosmologically short times.

We have so far had three eras of growth: forager, farmer, and industry. During the forager era, the number of foragers doubled about every quarter million years. During the farming era the number of farmers doubled about every thousand years. And during our industry era our economy has doubled about every fifteen years (Hanson 2000). In all three eras, growth was primarily caused by innovation. (In prior eras, population tracked economic growth and income remained near subsistence levels because populations could grow faster than did the economy.)

A thousand doublings of the economy seems plenty to create a very advanced civilization. After all, that would give a factor of ten to the power of three hundred increase in economic capacity, and there are only roughly ten to the eighty atoms in the visible universe. Yes, at our current industry rates of growth, we’d produce that much growth in only fifteen thousand years, while at farmer rates of growth it would take a million years.

But a million years is still only a small blip of cosmological time. It is even plausible for a civilization to reach very advanced levels while growing at the much slower forager rate. While a civilization growing at forager rates would take a quarter billion years to grow a thousand factors of two, the universe is thirteen billion years old, and our planet is four billion. So there has been plenty of time for very slow growing aliens to become very advanced.

Thus aliens tending to fall into cultures and institutions that discourage innovation is just not by itself a plausible explanation for the “great silence” of a universe without noisy advanced aliens. Even vastly lower rates of innovation are plenty enough to create very advanced aliens over cosmological times.

Perhaps one could have more success if one combined this slow-growth hypothesis with another hypothesis about very short time windows in which civilizations had to grow before something killed them off. But even then, I’m skeptical that wealth inequality matters much for rates of innovation.




John Asker, Joan Farre-Mensa, Alexander Ljungqvist (2011) Comparing the Investment Behavior of Public and Private Firms, NBER Working Paper No. 17394, September.

Gregory Clark (2014) The Son Also Rises: Surnames and the History of Social Mobility, Princeton University Press, February 23.

Robin Hanson (2000) Long-Term Growth As A Sequence of Exponential Modes, December.

Also from this issue

Lead Essay

  • David Brin criticizes the possibly reckless turn in recent SETI research. He also speculates on what the great silence may say about human societies. It may not be such a good idea to go about shouting to the cosmos - not when we have so little idea of what may be out there.

    That said, Brin speculates on the nature of any intelligent life we are likely to meet. He notes that our scientific and technological society is very unusual when compared to societies of the past: It is, he says, diamond-shaped, with relatively few at either the bottom or the top, and with a broad equality of social station, rights, and even wealth in the middle. Maintaining such a society is hard work, and one reason we seem to be alone in the universe may simply be that very few alien civilizations have escaped from feudalism or something like it.

Response Essays

  • Robin Hanson runs a cost-benefit analysis on our use of very loud radar signals. He finds that if there is even a small probability of a hostile civilization hearing us, then the risks are not worth the rewards. This conclusion holds up under fairly severe assumptions, and it grows much firmer as we consider our likely technological developments in the near future. Astronomy, moreover, is advancing rapidly, and it will likely tell us much more about the probability of existence and the nature of extraterrestrial life. When it does, we may have a better idea of the wisdom of sending out very loud radio signals. In the meantime, he concludes that yes, humanity should indeed shut the hell up.

  • We have few tools at our disposal to learn about intelligent extraterrestrials - if they even exist. But one relatively powerful tool is evolutionary psychology. Jerome H. Barkow reviews some findings from terrestrial evolutionary psychology and considers their implications for alien life. We will learn a lot if we can discover what aliens find sexy, he claims - because sexual selection has overwhelmingly influenced terrestrial animals, including ourselves.

    We will also learn a great deal by observing aliens’ predation history, their group cooperation, and their genetic transmission of culturally favored traits. Of course, these observations will have to wait for first contact. Barkow concludes by agreeing with Robin Hanson - until we know more, humanity should probably keep relatively quiet.

  • Douglas Vakoch argues that active SETI is not to be feared: If highly advanced civilizations exist out there, they will have highly advanced radio detection equipment. If they are anywhere near us, then they will have known about us for decades. Messaging them can do no more harm than what we have already done, and it may do us a great deal of good, particularly if these civilizations are waiting for us to make the first move, and if messaging them directly is the signal they need to initiate contact.